** May you share freely, never taking more than you give.
**
*************************************************************************
-** $Id: btree.c,v 1.202 2004/11/03 11:37:08 danielk1977 Exp $
+** $Id: btree.c,v 1.203 2004/11/04 02:57:34 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
memset(&data[24], 0, 100-24);
zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
pBt->pageSizeFixed = 1;
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( pBt->autoVacuum ){
+ put4byte(&data[36 + 4*4], 1);
+ }
+#endif
return SQLITE_OK;
}
}
}
+
+static int relocatePage(
+ Btree *pBt,
+ MemPage *pDbPage,
+ u8 eType,
+ Pgno iPtrPage,
+ Pgno iFreePage
+){
+ MemPage *pPtrPage; /* The page that contains a pointer to pDbPage */
+ Pgno iDbPage = pDbPage->pgno;
+ Pager *pPager = pBt->pPager;
+ int rc;
+
+ assert( eType==PTRMAP_OVERFLOW2
+ || eType==PTRMAP_OVERFLOW1 || eType==PTRMAP_BTREE );
+
+ /* Move page iDbPage from it's current location to page number iFreePage */
+ TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
+ iDbPage, iFreePage, iPtrPage, eType));
+ rc = sqlite3pager_movepage(pPager, pDbPage->aData, iFreePage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ pDbPage->pgno = iFreePage;
+
+ /* If pDbPage was a btree-page, then it may have child pages and/or cells
+ ** that point to overflow pages. The pointer map entries for all these
+ ** pages need to be changed.
+ **
+ ** If pDbPage is an overflow page, then the first 4 bytes may store a
+ ** pointer to a subsequent overflow page. If this is the case, then
+ ** the pointer map needs to be updated for the subsequent overflow page.
+ */
+ if( eType==PTRMAP_BTREE ){
+ rc = setChildPtrmaps(pDbPage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }else{
+ Pgno nextOvfl = get4byte(pDbPage->aData);
+ if( nextOvfl!=0 ){
+ assert( nextOvfl<=sqlite3pager_pagecount(pPager) );
+ rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+ }
+
+ /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
+ ** that it points at iFreePage. Also fix the pointer map entry for
+ ** iPtrPage.
+ */
+ rc = getPage(pBt, iPtrPage, &pPtrPage);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = sqlite3pager_write(pPtrPage->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(pPtrPage);
+ return rc;
+ }
+ modifyPagePointer(pPtrPage, iDbPage, iFreePage, eType);
+ rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
+ releasePage(pPtrPage);
+ return rc;
+}
+
/* Forward declaration required by autoVacuumCommit(). */
static int allocatePage(Btree *, MemPage **, Pgno *, Pgno);
u8 eType;
int pgsz = pBt->pageSize; /* Page size for this database */
Pgno iDbPage; /* The database page to move */
- u8 *pDbPage = 0; /* "" */
MemPage *pDbMemPage = 0; /* "" */
Pgno iPtrPage; /* The page that contains a pointer to iDbPage */
- MemPage *pPtrMemPage = 0; /* "" */
Pgno iFreePage; /* The free-list page to move iDbPage to */
MemPage *pFreeMemPage = 0; /* "" */
}
rc = getPage(pBt, iDbPage, &pDbMemPage);
if( rc!=SQLITE_OK ) goto autovacuum_out;
- pDbPage = pDbMemPage->aData;
/* Find the next page in the free-list that is not already at the end
** of the file. A page can be pulled off the free list using the
if( rc!=SQLITE_OK ) goto autovacuum_out;
assert( iFreePage<=origSize );
}while( iFreePage>finSize );
-
- /* Move page iDbPage from it's current location to page number iFreePage */
- TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n",
- iDbPage, iFreePage, iPtrPage, eType));
releasePage(pFreeMemPage);
pFreeMemPage = 0;
- rc = sqlite3pager_movepage(pPager, pDbPage, iFreePage);
- if( rc!=SQLITE_OK ) goto autovacuum_out;
- pDbMemPage->pgno = iFreePage;
- /* If pDbPage was a btree-page, then it may have child pages and/or cells
- ** that point to overflow pages. The pointer map entries for all these
- ** pages need to be changed.
- **
- ** If pDbPage is an overflow page, then the first 4 bytes may store a
- ** pointer to a subsequent overflow page. If this is the case, then
- ** the pointer map needs to be updated for the subsequent overflow page.
- */
- if( eType==PTRMAP_BTREE ){
- rc = setChildPtrmaps(pDbMemPage);
- if( rc!=SQLITE_OK ) goto autovacuum_out;
- }else{
- Pgno nextOvfl = get4byte(pDbPage);
- if( nextOvfl!=0 ){
- assert( nextOvfl<=origSize );
- rc = ptrmapPut(pBt, nextOvfl, PTRMAP_OVERFLOW2, iFreePage);
- if( rc!=SQLITE_OK ) goto autovacuum_out;
- }
- }
+ rc = relocatePage(pBt, pDbMemPage, eType, iPtrPage, iFreePage);
releasePage(pDbMemPage);
- pDbMemPage = 0;
-
- /* Fix the database pointer on page iPtrPage that pointed at iDbPage so
- ** that it points at iFreePage. Also fix the pointer map entry for
- ** iPtrPage.
- */
- rc = getPage(pBt, iPtrPage, &pPtrMemPage);
- if( rc!=SQLITE_OK ) goto autovacuum_out;
- rc = sqlite3pager_write(pPtrMemPage->aData);
if( rc!=SQLITE_OK ) goto autovacuum_out;
- modifyPagePointer(pPtrMemPage, iDbPage, iFreePage, eType);
- rc = ptrmapPut(pBt, iFreePage, eType, iPtrPage);
- if( rc!=SQLITE_OK ) goto autovacuum_out;
- releasePage(pPtrMemPage);
}
/* The entire free-list has been swapped to the end of the file. So
MemPage *pRoot;
Pgno pgnoRoot;
int rc;
+/* TODO: Disallow schema modifications if there are open cursors */
if( pBt->inTrans!=TRANS_WRITE ){
/* Must start a transaction first */
return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
if( pBt->readOnly ){
return SQLITE_READONLY;
}
+#ifdef SQLITE_OMIT_AUTOVACUUM
rc = allocatePage(pBt, &pRoot, &pgnoRoot, 1);
if( rc ) return rc;
-#ifndef SQLITE_OMIT_AUTOVACUUM
- /* Note: This is temporary code for use during development of auto-vacuum.
- ** There should be no need for a pointer map entry for root-pages.
- */
+#else
if( pBt->autoVacuum ){
+ Pgno pgnoMove; /* Move a page here to make room for the root-page */
+ MemPage *pPageMove; /* The page to move to. */
+
+ /* Run the auto-vacuum code to ensure the free-list is empty. This is
+ ** not really necessary, but it avoids complications in dealing with
+ ** a free-list in the code below.
+ ** TODO: This may need to be revisited.
+ */
+ rc = autoVacuumCommit(pBt);
+ if( rc!=SQLITE_OK ) return rc;
+
+ /* Read the value of meta[3] from the database to determine where the
+ ** root page of the new table should go. meta[3] is the largest root-page
+ ** created so far, so the new root-page is (meta[3]+1).
+ */
+ rc = sqlite3BtreeGetMeta(pBt, 4, &pgnoRoot);
+ if( rc!=SQLITE_OK ) return rc;
+ pgnoRoot++;
+
+ /* The new root-page may not be allocated on a pointer-map page. */
+ if( pgnoRoot==PTRMAP_PAGENO(pBt->pageSize, pgnoRoot) ){
+ pgnoRoot++;
+ }
+ assert( pgnoRoot>=3 );
+
+ /* Allocate a page. The page that currently resides at pgnoRoot will
+ ** be moved to the allocated page (unless the allocated page happens
+ ** to reside at pgnoRoot).
+ */
+ rc = allocatePage(pBt, &pPageMove, &pgnoMove, 0);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ if( pgnoMove!=pgnoRoot ){
+ u8 eType;
+ Pgno iPtrPage;
+
+ releasePage(pPageMove);
+ rc = getPage(pBt, pgnoRoot, &pRoot);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = ptrmapGet(pBt, pgnoRoot, &eType, &iPtrPage);
+ if( rc!=SQLITE_OK ){
+ releasePage(pRoot);
+ return rc;
+ }
+ rc = relocatePage(pBt, pRoot, eType, iPtrPage, pgnoMove);
+ releasePage(pRoot);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = getPage(pBt, pgnoRoot, &pRoot);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ rc = sqlite3pager_write(pRoot->aData);
+ if( rc!=SQLITE_OK ){
+ releasePage(pRoot);
+ return rc;
+ }
+ }else{
+ pRoot = pPageMove;
+ }
+
rc = ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0);
if( rc ){
- sqlite3pager_unref(pRoot->aData);
+ releasePage(pRoot);
+ return rc;
+ }
+ rc = sqlite3BtreeUpdateMeta(pBt, 4, pgnoRoot);
+ if( rc ){
+ releasePage(pRoot);
return rc;
}
+ }else{
+ rc = allocatePage(pBt, &pRoot, &pgnoRoot, 1);
+ if( rc ) return rc;
}
#endif
assert( sqlite3pager_iswriteable(pRoot->aData) );
int rc;
MemPage *pPage;
BtCursor *pCur;
+/* TODO: Disallow schema modifications if there are open cursors */
if( pBt->inTrans!=TRANS_WRITE ){
return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
}
/* The current implementation is unable to handle writes to an autovacuumed
** database. So make such a database readonly. */
+#ifdef SQLITE_OMIT_AUTOVACUUM
if( idx==4 && *pMeta>0 ) pBt->readOnly = 1;
+#endif
return SQLITE_OK;
}
projects / thirdparty / sqlite.git / commitdiff
